1. Field of the Invention
This invention relates to terminal devices for mobile communication and screen display methods performed by such devices and, more specifically, to a terminal device for mobile communication to carry out data communications with an external server through a digital network and to appropriately scroll a display element such as a character and image on a display screen included in the device, and a screen display method performed by such device.
2. Description of the Background Art
In recent years, with the widespread use of the Internet, documents written in description language such as HTML (Hypertext Markup Language) have been exchanged. As well known, such description language allows free arrangement of a plurality of display elements such as characters and images composing a document.
The HTML is standardized by W3C (World Wide Web Consortium) and standardization of HTML Ver. 4.0 has been complete. The details on the HTML are disclosed in http://www.w3c.org/.
In general, a document written in such description language is displayed or scrolled by using a document processing software called Web browser. Such Web browser is also incorporated in personal portable terminals such as PDAs (Personal Digital Assistants) having communication functions and cellular phones to allow wireless access to the Internet. Therefore, irrespective of wired or wireless, Internet access has become active for a wide variety of purposes such as exchanging electronic mails.
The display screen of the personal portable terminals is so small for the purpose of portability that only a limited number of display elements can be displayed. Further, the resolution of the display screen varies according to models. Therefore, to display elements that cannot be displayed on a single screen in such portable terminals, the screen is scrolled a line or page to sequentially display those-elements. Therefore, how the scrolled screen is viewable on a limited size of the display screen becomes very important.
For scrolling, a technique of scrolling and displaying a screen based on the size of characters is disclosed in Japanese Patent Laying-Open No. 10-187136 (1998-187136), although this publication is not specifically for personal portable terminals.
The technique disclosed in this publication relates to a document processing device that displays a document with a plurality of characters of different sizes mixed in one line on a display screen for editing and creating. To achieve such device, the document processing device includes at least a cursor to be displayed for specifying a position (line) of a desired character displayed on the display screen, a move instructing unit instructing movement one line upward or downward from the line where the cursor is located, and a scroll unit scrolling up or down the display screen according to an amount of movement based on the height of the character if the character to be displayed after cursor movement is supposed to be displayed across a boundary of the display screen. With these components, the technique disclosed in the publication allows scrolling so that the displayed characters will not be interrupted on the boundary of the display screen.
As described above, the display screen of the personal portable terminal is so small that display elements that can be displayed at a time are limited. On the other hand, a plurality of display element of different types can be freely arranged on HTML documents. Furthermore, these elements on HTML documents can be set so as to be selected by users (such as xe2x80x9cexecutexe2x80x9d and xe2x80x9csendxe2x80x9d).
However, free arrangement of display elements greatly increases the possibility of causing a problem that some of the display elements might be displayed across the boundary of the display screen when the display screen is scrolled up or down a line or page. Therefore, the number of display elements that can be recognized in their entirety is reduced, thereby disadvantageously inhibiting recognizable display elements from being displayed on a single screen. Another disadvantage is that users may have to select a selectable display element without recognizing it in its entirety.
The above problems cannot be solved even with the technique disclosed in the above publication as long as a plurality of display elements of different types can be freely arranged.
Therefore, an object of the present invention is to provide a terminal device for mobile communication that, when scrolling a display screen of a document which a plurality of display elements of different types are mixed, searches for a display element that is supposed to be displayed across the boundary of a display screen and appropriately corrects the amount of scrolling so that the display element is not across the boundary, and a screen display method performed by such device. Therefore, it is possible to increase the number of display elements that can be recognized in their entirety by users on the display screen, select a selectable display element while being recognized in its entirety by the users, and further provide more recognizable information to the user.
The present invention has the following features to solve the object above.
A first aspect of the present invention is directed to a terminal device for mobile communication enabling data communication with an external server through a digital network and displaying a document composed of display elements of different types such as characters and images. The terminal device comprises a reception unit operable to receive a scroll instruction for scrolling a display screen from a user, a basic amount determination unit, responsive to the scroll instruction from the reception unit, operable to determine a basic moving amount according to the scroll instruction, a display element information holding unit operable to hold information required for displaying the display elements composing the document, a display element searching unit operable to search the display elements for a reference display element that is supposed to be displayed across a boundary of the display screen if the display screen is scrolled based on the basic moving amount determined by the basic-amount determination unit, by using the information held by the display element information holding unit, an offset determination unit, operable to calculate an offset moving amount based on the reference display element found by the display element searching unit, a calculation unit operable to calculate an actual moving amount from the basic moving amount determined by the basic amount determination unit and the offset moving amount calculated by the offset determination unit, and a display processing unit operable to scroll the display screen according to the actual moving amount calculated by the calculation unit.
As described above, in the first aspect, when a document composed of display elements of different types is scrolled on the display screen, the display element that is supposed to be displayed across the boundary of the screen is searched, and the scrolling amount is corrected so that the display element should not be displayed across the boundary. Therefore, it is possible to in crease the number of display elements that can be recognized in their entirety by users on the display screen, select a selectable display element while being recognized in its entirety by the users, and further provide more recognizable information in the users.
According to a second aspect, further to the first aspect discussed above, the offset determination unit previously has priority information indicating priorities of the-display elements that are possibly referred to. If the display element searching unit finds a plurality of display elements that are possibly referred to, the offset determination unit calculates the offset moving amount based on one of the plurality of display elements that is determined as the reference display element according to the priority information.
As described above, in the second aspect, if display elements of different types are supposed to be displayed across the boundary of the screen, the scrolling amount is corrected with reference to the display element having the highest priority to be displayed. Therefore, it is possible to correct scrolling with reference to a compound element that enables a user to perform instructing operation, a text element whose characters should be recognized, and the like, thereby improving operability such as to prevent users from erroneous operation and to enhance element recognition.
According to third and fourth aspects, further to the first and second aspects, respectively, if the display element searching unit finds the display element that is predetermined not to be referred to as the reference display element, the offset determination unit calculates the offset moving amount without considering the display element.
As described above, in the third and fourth aspects, the display element that is predetermined not to be referred to is excluded. Therefore, scroll correction is faster.
According to fifth to eighth aspects that are preferable, further to the first to fourth aspects, respectively, the reception unit receives the scroll instruction for one-line/one-page vertical scrolling, and the basic amount determination unit determines the basic moving amount according to the scroll instruction for the one-line/one-page vertical scrolling.
According to ninth to twelfth aspects that are preferable, further to the fifth to eighth aspects, respectively, the display element searching unit takes an upper side of the display screen (a line between upper-left and upper-right 5 ends) as the boundary.
As described above, in the fifth to twelfth aspects, a typical technique for vertical scrolling is described. Therefore, it is possible to correct scrolling always with reference to the upper side of the screen.
According to thirteenth to sixteenth aspects, further to the ninth to twelfth aspects, respectively, the offset determination unit compares a height of the reference display element on and/or off the display screen with a predetermined reference value, and takes the height equal to or smaller than the reference value as the offset moving amount.
As described above, in the thirteenth to sixteenth aspects, scroll correction is made vertically based on the positional relation between the reference display element and the boundary. Therefore, scroll correction can be varied according to the displayed screen so as to become appropriate most.
A seventeenth aspect is directed to a method of displaying a document composed of display elements of different types such as characters and images using previously provided information required for displaying the display elements. The method comprises receiving a scroll instruction for scrolling a display screen from a user, determining a basic moving amount according to the scroll instruction, searching the display elements for a reference display element that is supposed to be displayed across a boundary of the display screen if the display screen is scrolled based on the basic moving amount, by using the information, calculating an offset moving amount based on the reference display element found in the searching step, calculating an actual moving amount from the basic moving amount and the offset moving amount, and scrolling the display screen according to the actual moving amount.
According to an eighteenth aspect, further to the seventeenth aspect, priority information indicating priorities of the display elements that are possibly referred to is previously provided, and if a plurality of display elements that are possibly referred to are found in the searching step, the offset moving amount is calculated in the offset moving amount calculating step based on one of the plurality of display elements that is determined as the reference display element according to the priority information.
According to nineteenth and twentieth aspects, further to the seventeenth and eighteenth aspects, respectively, if the display element that is predetermined not to be referred to as the reference display element is found in the searching step, the offset moving amount is calculated in the offset moving amount calculating step without considering the display element.
According to twenty-first to twenty-fourth aspects that are preferable, further to the seventeenth to twentieth aspects, respectively, in the instructing step, the scroll instruction for one-line/one-page vertical scrolling is received, and in the determining step, the basic moving amount is determined according to the scroll instruction for one-line/one-page vertical scrolling.
According to twenty-fifth to twenty-eighth aspects that are preferable, further to the twenty-first to twenty-fourth aspects, respectively, in the searching step, an upper side of the display screen (a line between upper-left and upper-right ends) is taken as the boundary.
According to twenty-ninth to thirty-second aspects, further to the twenty-fifth to twenty-eighth aspects, respectively, in the offset moving amount calculating step, a height of the reference display element on and/or off the display screen is compared with a predetermined reference value, and the height equal to or smaller than the reference value is taken as the offset moving amount.
As described above, in the seventeenth to thirty-second aspects, a screen display method performed by the terminal device for mobile communication in the first to sixteenth aspects is described. Applying this method to various terminal devices for mobile communication can produce useful effects as described above.